Examples with rangl

Michael D. Sumner

2016-10-19

Introduction

The ‘rangl’ package illustrates some generalizations of GIS-y and topology tasks in R with “tables”. See the package project for more information.

Get some maps and plot in 3D - in plane view, or globe view.

NOTE: these plots are interactive, but performance and quality will be better (for now) if run locally.


library(rgl)
library(maptools)
data(wrld_simpl)
library(raster)

## convert to triangles and plot 
library(rangl)
cmesh <- rangl(wrld_simpl)
plot(cmesh)
#> Joining, by = "object_"
#> Joining, by = "triangle_"

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sids <- raster::shapefile(system.file("shapes/sids.shp", package="maptools"))
#> Warning in .local(x, ...): .prj file is missing
projection(sids) <- "+proj=longlat +ellps=clrk66"

ex <- extent(sids) + 5
gl <- graticule::graticule(seq(xmin(ex), xmax(ex), length = 15), 
                           seq(ymin(ex), ymax(ex), length = 8))


## convert to triangles, but wrap onto globe then plot
smesh <- rangl(sids)
plot(globe(smesh))
#> Joining, by = "object_"
#> Joining, by = "triangle_"
mgl <- rangl(gl)
mgl$o$color_ <- "black"
plot(globe(mgl), lwd = 2)
#> Joining, by = "object_"
#> Joining, by = "segment_"

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Holes are (trivially) supported.

It’s trivial to have “holes”, because there are no holes, because we have a true surface, composed of 2D primitives (triangles).

library(spbabel)
data(holey)

## SpatialPolygonsDataFrame
sph <- sp(holey)

glh <- rangl(sph)
plot(glh)
#> Joining, by = "object_"
#> Joining, by = "triangle_"

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Lines are supported.

linehouse <- as(sph, "SpatialLinesDataFrame")
plot(rangl(linehouse))
#> Joining, by = "object_"
#> Joining, by = "segment_"

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Globe lines

lmesh <- rangl(as(wrld_simpl, "SpatialLinesDataFrame"))
plot(globe(lmesh))
#> Joining, by = "object_"
#> Joining, by = "segment_"

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rgl objects

Rgl mesh3d objects that use “triangle” primitives are supported.

library(rgl)

dod <- rangl(dodecahedron3d(col = "cyan"))
octo <- rangl(translate3d(octahedron3d(col = "blue"), 6, 0, 0))
plot(dod, col = viridis::viridis(5)[1], alpha = 0.3)
#> Joining, by = "object_"
#> Joining, by = "triangle_"
plot(octo, col = viridis::viridis(5)[5], alpha = 0.3)
#> Joining, by = "object_"
#> Joining, by = "triangle_"
bg3d("grey")

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To complete the support for these rgl objects we need quads, and to allows a mix of quads and triangles in one data set (that’s what extrude3d uses). Extrusion is a bit limiting so it’s unclear how useful this is (yes it is common, though). See rgl::extrude3d for the most readily available method in R.

Points

And points work! (Don’t laugh).

library(rangl)
library(maptools)
data(wrld_simpl)
mpts <- as(as(wrld_simpl, "SpatialLinesDataFrame"), "SpatialMultiPointsDataFrame")
plot(rangl(mpts))
#> Joining, by = "object_"
#> Joining, by = "branch_"
rgl::view3d(theta = 25, phi = 3)

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Trips

The trip package includes a ‘walrus818’ data set courtesy of Anthony Fischbach. Zoom around and see if you can find them.

library(trip)
library(rangl)
data(walrus818)

library(graticule)
prj <-"+proj=laea +lon_0=0 +lat_0=90 +ellps=WGS84"
gr <- graticule(lats = seq(40, 85, by = 5), ylim = c(35, 89.5), proj = prj)
library(maptools)
data(wrld_simpl)

w <- spTransform(subset(wrld_simpl, coordinates(wrld_simpl)[,2] > -70),  prj)
library(graticule)
walrus <- spTransform(walrus818, prj)

gr$color_ <- "black"
rgl::par3d(windowRect = c(100, 100, 912 + 100, 912 +100))
plot(rangl(gr))
#> Joining, by = "object_"
#> Joining, by = "segment_"
w$color_ <- sample(viridis::inferno(nrow(w)))
plot(rangl(w), specular = "black")
#> Joining, by = "object_"
#> Joining, by = "triangle_"
plot(rangl(walrus))
#> Joining, by = "object_"
#> Joining, by = "segment_"
um <- structure(c(0.934230506420135, 0.343760699033737, 0.0950899347662926, 
                  0, -0.302941381931305, 0.905495941638947, -0.297159105539322, 
                  0, -0.188255190849304, 0.24880850315094, 0.950081348419189, 0, 
                  0, 0, 0, 1), .Dim = c(4L, 4L))
par3d(userMatrix = um)

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